Universal flight indicator



Jan. 27, 1942. SPERRY, JR

UNIVERSAL FLIGHT mnxcmon Filed Dec. 3, 1938 3 Sheets-Sheet 2- Z 5 f7 I I! I .58

1 P n z! 42 I5 '46 22 .57 as Z3 25 52 F163.

l I T i' P INVENTOR BY WA ATTORNEY Jan. 27, 1942. E. A. SPERRVY. JR 1, Q

UNIVERSAL FLIGHT INDICATOR Fired Dec. 3, 193a s Sheets-Sheet 3 INVENTOR 42 m? A. .SPR/FYJ/R a u I 2 EATTORNEY sensitive'element I U v with respect to the pivotal; center of movement "regardless of the angular relationship: e risting I v c v d the said-can ter of pivotal movement.

Patented Jan. 27, 1942 UNITED STATE 5 PATENT orator:

UNIVERSAL FLIGHT mmca'roa Elmer a. Sperry, Jr., New York, N. 1., eit er a,

Sperry Products, Inc., Hoboke ,N. 8., a corporation of New'York 1' Application December 3,1938, Serial No. 243,!!!

3 Claims; (Circa-159) .7

This invention relates'to universal flight instruments such as magnetic compasses and artificial horizons, particularly those types :wherein a; buoyant element issupported for universal pivot. Suchadevice movement around a fixed is disclosed, for example, in my copending ap-v tlon applied thereto.

ofuniversal flight instrument, showing inven- Fig; 2 is a sectionshowing af detail oi the Fig. 1

' mechanism in enlarged form, i

plication Ser. No, 140,650 illed May 4, 1937. In said application there is disclosed a universal Fig. 3 is an enlargedjelevation of the lower portion of thelcaging device,

. Fig. 4 is a vertical 1- l v 3 ..'C j Fig. 51s a view siniilaratofigAbut showin a different. angularrelationship between; the sensitive element and the pivot post. 1

' I have illustrated my inv ntiongin connection with'a magnetic compasswhich may be of the tion Ser.

thesensitive' element settles to'give' a useful' indication. It is thereforev desirable that the. sensitive element be protected against such wide displacements during unusual movements of the craft. For this purpose, it" is once! the principal objects of myinvention'to provide means whereby such a universally supported sensitive may be locked or caged in relatively fixed position with respect to the aircraft-during such maneuvers. v v I As described in thefsaid copending application, the sensitive elementi'n such instruments,

when supported upon a pivot, should, prior to the tim'e that the penduiouselement is attachedv general type described copendina I v mplicament of the "invention which ishered scribed is merely illustrative and' the. principle thereof applies in general to all typesof instruments embodying the essential elements ,of a universally pivoted inertia member which .isIH-heldinen'gagement with its pivot by buoyancyvor gravity. The

element in an instrument of the type described. a

magnetic compass shown consists essentially of parts. First, an inertia elementjinthe form of a magnetic :meridian V seeking element; second, a pendulous element; and, third, means for supporting the pendulous element-on the magnetic element. The inertia ormagnetic element "consistsof a magnet systemand.-=a-float upon thereto, be balanced with respe t to the pivotal center of'movement. Thishasiheretofore been 'diiiicult with the types oipivots which have been employed, and it is therefore a further obiect of my invention to" provide a pivot in an instrument of the type vdescrib'ed wherein the between the sensitive 'elemep means whereby a ivoted, sensitiveeiement, free-v ly supportedupon said'pivot: by buoyancy or gravity.

tances with respect to the sensitive element.

Further objects and advantages of this invention will become apparent in the following detailed description thereof.

In the accompanying drawings,

Fig. l is a vertical section through a form 55 will t me 'b 'iba y ,Itis a'further lobj'cctoi in en pro.

videin a device of the type d ,iniproved 5 maybe prevented fromdiseng'agingits 7 c f point of pivotal support evenjthough the pivot post moves through relativelywide angular disc which the magnet system is supported. The float may be of the type disclosed in my'copendingappiication Ser. No. 183,550, iiledgllanuary 5, 1938, which consists of aninner sealed circum- 'ferential Ifloat chamber li -which provides the necessary buoyancy and is surrounded by an outer: chamber all whichkis filled with liquid which" enters through top and bottom ports 12 and IIMIn this manner the float obtains the i" desirable quality offlarge inertia due to the fact that liquid is substantially trapped" in the outer chamber while a minimum of. buoyancy is employedlthe.buoyancyoi chamber II and the 'dispiacement of. the float: and therefore .a minimumv-ofbuoy'anc chanle ob-- tained in response to variations initm rature. 'I'hisisv important because the float is supported by a pivot Ii restins Mainst a jewel l6 in the bottom of a pivot post :1 which is fixed within liquid-filled casing'C. As the-float with its'pivot It varies its buoyancy, it will vary the pressure which the host exerts against the jewel ll of the pivot post 1, and lithe-entire chamber Ii were buoyant there wouldibe such a l varia- I tion in buoyancy in response 'eerature change that the pivotal pressure attach the H I tioriithroughfthe novel pivot constituting.myg-invention and disclosed.

No. 140,650, but- .the form (i embodi-' pivot post would at times become so ent efiicient operation of the the construction shown here claimed in my said copencl 183,556, I obtain the iarge moment of inertia ens ire element, and hence lack of re- 12s.; to short-period disturbing forces a" minimum variation in buoyancy in response to temperature changes. The casing C is filled with fluid so that the outer chamber ii of the heat member will always be full of liquid which can enter and leave by openings i2 and is which are large enough to permit such movement of liquid in response to temperature changes but which substantially trap the liquid within the chamber ii so that ,said'liquid acts to increasethe inertia of the float element. The float is formed with an inner cylindrical hollow chamber within which is mounted the supporting flange 2| which suppofitsa plate 22 carrying the pivot IS. The said" pivot is fitted into a socket 23- whlch is'iuturn screwed into the supporting plate ,22 and th'eheight of the pivot point may be adjusted by means of shims ,po sedbetween the bottorn of socket 23 and the intersuppo'rting' plate 22'. This adjustment is for the purpose of bringing the center of the pivot into predetermined relationship with the center of gravity and center of buoyancyof the sensitive element.- For thispurpose, also, a lateral adjustment of plate-22 on'I supporting plate 2! is provided, a lower flange 24 being provided so that plate 22"mayqmove laterally between members 2 i and 24 and may-belocked in adjusted posi- 'tion byscrewsfis, adjustment together with- :the vertical acflustment by means o'fshims 25 .1 enables'th center of g avity and center of buoy- I ancy' of l the sensitive 1 element thus far: idescribed tobe brought-intoany desired relationship with 1 the center of pivotal'm'ovement; Also} supported in the'said cylindrical interior 2!! 'oisthe floatare bearings 26 in' whichis'jou'rnalled a shaft 21 carrying magnets 28 adjacen t its' opposite ends so that said'rna'gne'ts'may beiree to take up their natural angle of dip; The supporting 'fiange 2| may be cut out as shownat 29 to provide spaces within which the magnets may-operate. I A

The pendulo'usj element may consist of a small weight 32 suspended by threads 33 from the pla te tain of thethreadspivot around their point of of buoyancy and therefore with 22 to which said strings are attached, The g threads form a cone which is rigid within a few degrees of ,displacement, but when the acceleration forces exceed aprcdetermineddegree, certhe sensitive element prior to attaching the pendulous element thereto, to coincide with the center of pivotal movement. In order that this relationship shall be at all times maintained regardless of the angular relationship existing between the sensitive eiement and the pivot post P, I cause the head (see Fig. 5) of the pivot it to, be formed as nearly hemispherical as it is possible to construct thesarne, and 3 cause the center of gravity and thecenter of buoyancy of the sensitive element to coincide with respect to the center 48 of the hemispherical tip which is also the center of pivotal movement of the sensitive element. The faces of jewel it are tangential ,tothe hemispherical center in which the head 4B of the pivot post normally rests (see Figs. 4 and 5). In this manner it will be seen that no matter what angular relationship exists between the sensitive element and the pivot post P; the center of gravity and center of buoyancy of the sensitive element will bear the same unchanging relation with respect to the center ll of pivotal movement.

The faces of the jewel it are cut so as to allow a wide angle of movement of the pivot post P relative to the sensitive element, in the present instance this angle being shown as fully to either side of the vertical. It will be understood that this makes a shallow cup out of the pivotal bearing and that th'ere may be a tendency for the pivot post to l'eave the pivot cup in response to Jars when the angular displacement becomes sumciently large;" In order to obviate such occurrence, I have shown in my prior and cop'ending application Ser.- No. 140,650, a retaining casing which encloses the two parts of the pivot, namely, the pivot point and the cup. In the present instance I have shown an improved retaining construction wherein only onemovablemember is employed in connection with'one fixed member. The movable member 42 may take a substantially hemispherical form surrounding the pivot post P and have an-opening 48 large enough to permit wide angle displacement. The said hemispherical movable member 42 is provided with an outwardly extending flange 44 adapted to engage an inwardly extending'fiange 45 on a socket member 46 threaded into the socket member 23.. Thus it will be seen that the pivot I5 is prevented from escaping from the cup l6 by reason of. the movable retaining "member 2 which in turn is locked in positionby the fixed retaining member 45.

As stated in the introduction, a construction of a universal flight instrument such as de- 'scribed has a long periodsensitive element attachment 3 l'while others ofthe threads become loose so that no "further torque is applied. to the sensitive element by the pendulous eleinent. The outer surface of float. chamber-ml l may carry the ne'cessary indicia which may be read in conjunction with vertical and horizontal lubber lines 35, 36 viewed vthrough observation wiudowii. V Various forms-of -pi'vots have been utilized in magnetic compasses and similar. instruments wherein a'pivoted sensitive element is'employed,

just described In such instrument" the sensitive element is carefully balanced to maintain a predetermined relation with respect to the cenbut none of *these "has' fbeen found adequate for the purposes of an instrument such as I have ter of pivotal movement. In the present instance such predetermined relation consists in causing the center of gravity and center of buoyancy of which, if displaced fromits normal position to lanfappreciable-degree, will take along-time to settle back .into its proper indicating position.

.Thus, in military maneuvers where planes make very rapid movements, 'suchas at times diving straight downwardly,.looping the loop and barrel-rolling, it may be desirable to provide means for locking the'parts of the instrument against such movements and thus avoid large displacemerits of the sen sitive element requiring a long time for settling. For this purpose I have shown a caging device which may take the form of a sleeve 50 surrounding the pivot post P and slideable thereon, said sleeve 50 being provided with a plurality of prongs 5| at the lower end thereof, adapted to engage in corresponding sockets 52 in the supporting plate 22. The sleeve,

50 for this purpose may be moved axially of the pivot post P by means of a knob 53 at the upper end of a post "extending through a packing 55 in casing C and having at its lower end -a gear 56 meshing with the gear 51 on sleeve 80. The, gear 56 is journaled in a plate I carried by the sleeve 50 and connected to the plate by means of a nut El, so that as knob 53 ismoved upwardly and downwardly, plate 80 and hence sleeve 50 will also'be moved upwardly and downwardly. The sleeve 60 may be rotated until prongs 5| find their sockets 52 by rotating knob 53 to rotate gearing 58, 51 and hence sleeve ill.

outwardly and the pivot i5 reengages in pivot cup o it.

The sensitive element will not have been appreciably displaced and hence will be ready to indicate properly after a very brief interval.

In accordance with the provisions of the patent statutes, 1 have herein described the prin- .ciple and operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that th invention can be carried out by other equivalent means. Also. while it is designed to use the various features and elements in the combination and relations described, some of these may be altered and others omitted without interfering with the more 1- general results outlined, and the invention extends to such use.

Having described my invention, what I claim and desire to secure by Letters Patent is:

1. In a universal night indicator comprising a casing filled with fluid, a buoyant sensitive element in said fluid including a pendulous membar, said element having a pivot. a bearing carried by said casing, said pivot engaging said bearing to permit relative movement between said element and said bearing, the portion of said-pivot which engages said bearing in any position or the element relative to said bearing having the form of aportion of a Sphere and i the portion of said hearing which said pivot engages also having the form of a portion of a sphere of substantially the same radius as said portion of said pivot whereby the center or movement of saidelement is the center oi said spherical portion. the portions of said bearing adjacent the spherical portion thereof being substantially tangent to said spherical portion, said element, exclusive of said pendulous member, having the center of gravity and center of buoyancy thereof coincident with the center of movement. i

2.'In a universal flight indicator, a casing, a sensitive element, said casing and said sensitive element having cooperating members in the form of a bearing fixed to said casingand a pivot carried by said element and adapted to engage said bearing to permit relative movement between said element and said bearing, and means for preventing disengagement of said pivot from said bearing during wide angular relative movements, which consists oi a two part retaining casing, one of said parts being supported on one of said vrelatively movable members and substantially enclosing said pivot and said bearing, and the other of saidparts substantially enclosing said first part and being fixed with respect to the other oi, said relatively movable members, said second part being adapted to engage said first part after a predetermined relative angular movement between said members, and said first part having a lost motion connection to the respective member on which it is supported whereby said members may move through a iurthe relative angular distance. a

3. In a universal flight indicator, a casins. a sensitive element, said casing and said element having cooperating members in the form or a bearing fixed to said casing and a pivot carried by said element and adapted to engage said bearing to permit relative movement between said element and said bearing, and means for preventing dise'ngagement of said pivot from said bearing during wide angular relative movements, which consists of a two-part retaining casing, .one of said parts being movably supported on one of said relatively movable members and substantially enclosing said pivot and said bearing, the other oi said parts substantial-- ly enclosing said first part and being iixed with respect to the other of said relatively movable members, said fixed part being adapted to engage said movable part after a predetermined relative angular movement of said members, the movable mounting of said movable part having means permitting said members to move through a further relative angular distance.

ELMER A. SPERRY, JR. 

